Neutral complex cleaning solution and regeneration method for denitration catalyst with calcium poisoning

Abstract

The invention belongs to the field of nitrogen oxide control in environmental protection science and technology, and particularly relates to the field of regeneration and utilization of SCR denitration catalyst with calcium poisoning, that is a neutral complex cleaning liquid and a regeneration method for denitration catalyst with calcium poisoning. The present invention uses a neutral polyether surfactant as a regeneration and calcium removal reagent to achieve a poisoned catalyst regeneration method with high calcium removal rate, low loss rate of active components and excellent recovery of denitrification activity; wherein the content of the polyether surfactant is in the range of 0.1-1 wt %; by the regeneration method of the present invention, the loading of active components which is required in the conventional regeneration process can be omitted, while the corrosion of equipment and catalyst can be reduced, thus capable of regenerating the denitration catalyst with high efficiency.

Claims

1. A regeneration method of denitration catalyst with calcium poisoning, comprising the steps of: (a) providing a neutral complex cleaning solution comprising active ingredients of polyether surfactant, wherein said polyether surfactant is NP-10 (POLYETHYLENE GLYCOL TRIMETHYLNONYL ETHER); (b) removing impurities remaining on a surface and inside pores of a poisoned denitration catalyst and drying under room temperature; (c) after drying, placing the poisoned denitration catalyst in the neutral complex cleaning solution for carrying out an ultrasonic cleaning process for 30 min-2 h and then allow it to stand for 1-24 h; and (d) after standing, taking out the denitration catalyst and processing washing, air drying, heat drying, and calcination to obtain a regenerated denitration catalyst.

2. The regeneration method of denitration catalyst with calcium poisoning according to claim 1, in the step (c), the solid to liquid ratio is 1:10-1:100, the cleaning time is 0.5-2 h, the cleaning temperature is 20° C.

3. The regeneration method of denitration catalyst with calcium poisoning according to claim 1, wherein in step (c), further comprising the substeps of: washing with deionized water, air drying until a water content is below 15-30%, heated drying under 80-160° C. for 12-72 hours, and then increasing temperature to 500-700° C. at a rate of 1-10° C./min and carrying out calcination under air condition for 4-24 hours to obtain the regenerated denitration catalyst is carried out after taking out the denitration catalyst.

4. The regeneration method of denitration catalyst with calcium poisoning according to claim 1, wherein said neutral complex cleaning solution consists of 0.1-1 wt % of polyether surfactant and deionized water.

5. A regeneration method of denitration catalyst with calcium poisoning, comprising the steps of: (a) providing a neutral complex cleaning solution comprising active ingredients of NP-10 (POLYETHYLENE GLYCOL TRIMETHYLNONYL ETHER) serving as a polyether surfactant; and (b) cleaning a poisoned denitration catalyst with calcium poisoning by using the neutral complex cleaning solution, thereby a denitration efficiency of about 90% and a calcium removal rate of about 88% is achieved while a loss of active ingredients of the poisoned denitration catalyst is minimized.

6. The regeneration method of denitration catalyst with calcium poisoning according to claim 5, wherein said neutral complex cleaning solution consists of 0.1-1 wt % of polyether surfactant and deionized water.

7. The regeneration method of denitration catalyst with calcium poisoning according to claim 6, further comprising the steps of: before step (b), removing impurities remaining on a surface and inside pores of the poisoned denitration catalyst and drying under room temperature until the poisoned catalyst is dried; in step (b), the cleaning process is an ultrasonic cleaning process which is carried out for 30 min-2 h, and after step (b), allowing standing time of 1-24 hours.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(1) The present invention is described in further detail below with reference to specific embodiments.

(2) The catalyst used in the following embodiments are prepared in a laboratory where the mass of V.sub.2O.sub.5 (Vanadium pentoxide) is 1%, the mass of WO.sub.3 (Tungsten trioxide) is 9%, the mass of CaO (Calcium oxide) is 4%, and the remaining is TiO.sub.2 (Titanium dioxide).

Embodiment 1

(3) A high-efficiency complex regeneration method for denitration catalyst with calcium poisoning, comprising the steps of:

(4) Step 1: using compressed air to clean a deactivated catalyst with a cross-section of 150×150 mm, a number of holes of 18×18 and a length of 800 mm;

(5) Step 2: dissolving 500 g of NP-10 (POLYETHYLENE GLYCOL TRIMETHYLNONYL ETHER, also known as OP-10, CAS number: 127087-87-0) in 100 L of deionized water and the NP-10 solution has a mass fraction of 0.5%, then placing the dried deactivated catalyst obtained from the Step 1 in the NP-10 solution for carrying out ultrasonic cleaning for 30 min and then allowing the deactivated catalyst to stand for 3 hours, and taking out and draining; and

(6) Step 3: Taking out the catalyst after Step 2, washing with deionized water for 3-4 times, air drying until a water content is below 20%, heated drying under 110° C. for 12 hours, and then increasing temperature to 500° C. at a rate of 2° C./min and carrying out calcination under air condition for 4 hours to obtain the regenerated catalyst.

Embodiment 2

(7) A high-efficiency complex regeneration method for denitration catalyst with calcium poisoning, comprising the steps of:

(8) Step 1: using compressed air to clean a deactivated catalyst with a cross-section of 150×150 mm, a number of holes of 18×18 and a length of 800 mm;

(9) Step 2: dissolving 100 g of EL-60 (cremophor EL 60) in 100 L of deionized water to obtain an EL-60 solution having a mass fraction of 0.1%, then placing the dried deactivated catalyst obtained from the Step 1 in the EL-60 solution for carrying out ultrasonic cleaning for 60 min and then allowing the deactivated catalyst to stand for 3 hours, and then taking out and draining; and

(10) Step 3: Taking out the catalyst after Step 2, washing with deionized water for 3-4 times, air drying until a water content is below 15%, heated drying under 110° C. for 12 hours, and then increasing temperature to 550° C. at a rate of 5° C./min and carrying out calcination under air condition for 4 hours to obtain the regenerated catalyst.

Embodiment 3

(11) A high-efficiency complex regeneration method for denitration catalyst with calcium poisoning, comprising the steps of:

(12) Step 1: using compressed air to clean a deactivated catalyst with a cross-section of 150×150 mm, a number of holes of 18×18 and a length of 800 mm;

(13) Step 2: dissolving 1000 g of AEO9 (polyethyleneglycol (9) mono-dodecyl ether) in 100 L of deionized water to obtain an AEO9 solution having a mass fraction of 1%, then placing the dried deactivated catalyst obtained from the Step 1 in the AEO9 solution for carrying out ultrasonic cleaning for 30 min and then allowing the deactivated catalyst to stand for 3 hours, and then taking out and draining; and

(14) Step 3: Taking out the catalyst after Step 2, washing with deionized water for 3-4 times, air drying until a water content is below 30%, heated drying under 110° C. for 12 hours, and then increasing temperature to 550° C. at a rate of 2° C./min and carrying out calcination under air condition for 6 hours to obtain the regenerated catalyst.

(15) The denitration efficiency of the regenerated catalyst of Embodiments 1-3 and the spent catalyst are compared, and the Ca removal rate, the V.sub.2O.sub.5 loss rate, and the WO.sub.3 loss rate are measured by ICP-OES test.

(16) Catalyst denitration rate, Ca removal rate, V.sub.2O.sub.5 loss rate and WO.sub.3 loss rate are calculated according to the following formula:
Denitration efficiency η=([NO.sub.X].sub.in−[NO.sub.X].sub.out)/[NO.sub.X].sub.in×100%
Ca removal rate c=([CaO].sub.poisoned−[CaO].sub.regenerated)/[CaO].sub.poisoned×100%
V.sub.2O.sub.5 loss rate v=([V.sub.2O.sub.5].sub.poisoned−[V.sub.2O.sub.5].sub.regenerated)/[V.sub.2O.sub.5].sub.poisoned×100%
WO.sub.3 loss rate w=([WO.sub.3].sub.poisoned−[WO.sub.3].sub.regenerated)/[WO.sub.3].sub.poisoned×100%

(17) Where: [NO.sub.X].sub.in is the NOx concentration (ppm) at the inlet of the reactor before the reaction, and [NO.sub.X].sub.out is the concentration (ppm) of the Nox in the outlet gas after the reaction. The test conditions are: temperature 350° C., atmospheric pressure, reaction space velocity 60000 h-1, catalyst input 0.2 g, flue gas concentration 500 ppm NH.sub.3, 500 ppm NO, 3% O.sub.2; [CaO].sub.poisoned is the percentage of calcium in the poisoned catalyst (calculated as CaO) [CaO].sub.regenerated is the percentage of calcium in the regenerated catalyst (calculated as CaO); [V.sub.2O.sub.5].sub.poisoned is the percentage of vanadium oxide in the poisoned catalyst, [V.sub.2O.sub.5].sub.regenerated is the percentage of vanadium oxide in the regenerated catalyst. [WO.sub.3].sub.poisoned is the percentage of tungsten oxide in the poisoned catalyst, and [WO.sub.3].sub.regenerated is the percentage of tungsten oxide in the regenerated catalyst.

(18) The table below summarizes the experimental results of the above embodiments:

(19) TABLE-US-00001 Denitration Ca removal V.sub.2O.sub.5 WO.sub.3 Embodiment efficiency (%) rate (%) loss rate (%) loss rate (%) 1 90.1 88.1 11.8 1.1 2 75.0 76.5 2.1 2.8 3 69.6 87.2 1.6 0.5